In MBMS services, a terminal residing in a cell, especially in the boundary area of a cell, may simultaneously receive identical MBMS signals from multiple cells. In order to achieve the purposes of increasing receive gain and improving signal receiving effect, with the identical MBMS signals, there are two configuration modes for the time slots of the carrier frequency that carries the MBMS service. One mode is the MBMS single frequency network (MBSFN) mode, also known as the SFN mode, that is, for a same MBMS service all the neighboring base stations use a same scrambling code and synchronously transmit identical radio signals. As shown in FIG. 9, the signals on the same channel 6 are simultaneously transmitted to a terminal through path 61 and path 62, respectively. Accordingly, the terminal treats the signals from different base stations as multi-path signals, and performs over-the-air signal combining on the multi-path signals to achieve the purposes of increasing receive gain and improving signal receiving effect. The other mode is the chip combining mode, that is, for a same MBMS service, each base station uses its own scrambling code to scramble the signals, and the base stations synchronously transmit different radio signals of the same content data. Accordingly, the terminal uses the chip combining mode, i.e. the multi-cell joint detection method, to perform chip-level combining on the different received radio signals of the same content data, so as to achieve the purpose of improving signal receiving effect.
According to the combining mode of the base station configuration described above, the configuration mode of MBMS carrier frequency time slots utilized by a base station determines which scramble mode is used in MBMS services by the base station, and which mode is used by the terminal to perform combining. Hence, the terminal needs to choose corresponding combining mode on the basis of the configuration mode of the MBMS carrier frequency time slots of its cell.
The conventional method for enabling the terminal to be aware of the configuration mode of the MBMS carrier frequency time slots of the base station is detailed as follows: a radio network controller (RNC), by setting the value of the information unit “MBSFN only service” in the system information broadcast 3 (SIB3), enables the terminal to obtain the MBMS of the base station; when the value of “MBSFN only service” is 1, it shows that the cell carries an MBMS service and all of the time slots within the cell use the SFN configuration mode. The user equipment (UE) reads the information unit in SIB3, and then knows that all of the time slots within the cell are configured with the SFN mode. Thus the terminal does not need to further perform operations such as same/different-frequency measurement, neighboring cell information reading, etc.
The shortcomings of the conventional method include: when part or all of time slots are configured as the chip mode, the terminal can not obtain the configuration mode of MBMS service carrier frequency time slots of the base station; for terminals that are not capable of performing chip combining, useless operations such as reading the chip-combining-related information from neighboring cells are still carried out, thus increase the load on the terminal. Therefore, there is a need for a method and system to overcome these shortcomings.